Wheel nut assembly

ABSTRACT

A wheel nut assembly for fixing a wheel to a vehicle hub. The wheel nut assembly has a wheel nut. The wheel nut has an internal thread. The wheel nut assembly further includes a wheel stud having an external thread adapted to co-operate with the internal thread of the wheel nut. The wheel stud further has an internal thread. A retaining member has an external thread of an opposite hand with respect to the internal thread of the wheel stud for cooperating with the internal thread of the wheel stud. A locking member is adapted to engage both the retaining member and the wheel nut to prevent relative movement there between and is further adapted to permit a location of the retaining member to be visually identified when the locking member is engaged to both the retaining member and the wheel nut.

FIELD OF THE INVENTION

This invention relates to improvements in a method and apparatus formounting and retaining a wheel onto a hub, and in particular relates tofixings for vehicle wheels.

DESCRIPTION OF RELATED ART

It is known to fix a wheel onto a vehicle hub using a plurality of wheelstuds which are fixed to the hub and a plurality of wheel nuts with onenut provided for each stud. The studs usually have an external threadedportion which is adapted to co-operate with a corresponding internalthreaded portion of the wheel nut. Such a wheel nut assembly willhereinafter be referred to as being of the kind set forth.

Modern vehicle wheels, especially those for use on commercial vehicles,comprise a rim portion and a nave or wheel disc. The nave joins the rimto the wheel centre, and is welded to the rim. Alternatively, one piecewheels are sometimes employed in which the rim and the nave are integralparts. To assemble the wheel to the vehicle hub, the wheel is firstpositioned so that the wheel is concentric with the hub and the wheelstuds project through openings in the nave or disc. The wheel nuts arethen tightened onto the studs. Because the nuts are of a larger diameterthan the openings through which the studs are passed, the wheel isfirmly clamped in place, by the nut against the hub.

Whilst the wheel nut assembly of the kind set forth is widely used tomount wheels on vehicles, there is a serious problem with the nutsworking loose. In a worst case, if all the nuts work loose, the wheelcan release itself from the hub with potentially catastrophic results.In practice, even if only one of the nuts retaining a wheel is loose,this will place extra loading on the adjacent nuts which causes them tostart to work loose. It is not unknown for a whole wheel to work freewithin 20 minutes of a single nut starting to vibrate loose.

One solution to the problem of wheel loss is taught from British patentapplication GB 9701533.3. In this application, a wheel nut assembly isprovided of the kind in which a wheel stud is adapted to receive a wheelnut of a first handed thread. The wheel nut also includes a bore with aninternal thread of opposite hand to that which receives the wheel nut.This opposite hand thread receives a looking bolt or retaining member. Alocking cap is then placed over both the wheel nut and the retainingmember. This locking cap co-operates with both the cap and the wheelnut. Because the wheel nut and retaining member have opposing threadsthe nut will not work free. A small retaining magnet located in the capholds it securely in place.

Whilst the above arrangement provides a significant improvement over theexisting art the applicant has appreciated that in its most rudimentaryform as outlined above several disadvantages are present over the use ofa simple wheel nut assembly. Firstly, because the cap covers the wheelnut and retaining member, a visual inspection of the location of the nutor retaining member cannot be made without first removing the cap. Thisis time consuming for a set of nuts on a wheel. Secondly, the magnet maywork loose from its fastening onto the cap. Finally, in cases where thecap is shaped to resemble a hexagonal nut for aesthetic reasons, adriver may attempt to “tighten” the cap with a wrench under the mistakenbelief that it is a wheel nut. This can cause catastrophic damage to thecap. Even if the cap is removed, the provision of the retaining membermay impede location of a socket body onto the wheel nut for tightening.

SUMMARY OF THE INVENTION

It is an object of at least one aspect of the present invention toameliorate one or more of the above mentioned problems.

In accordance with a first aspect, the invention provides a wheel nutassembly comprising:

a wheel stud having a first portion having a first external thread whichis adapted to co-operate with an internal thread provided on a wheel nutand a second portion having a thread of the opposite hand to the firstexternal thread which co-operates with a retaining member having athread which is of the same hand as the second threaded member, and

a locking member which is adapted to engage both the retaining memberand the wheel nut to prevent relative movement therebetween, and inwhich the locking member is so constructed and arranged to permit thelocation of the retaining member to be visually identified whilst thelocking member is in place.

Preferably, the locking member comprises a cap that may completely orpartially cover the wheel nut and the retaining member. The cap may beprovided with an opening which permits viewing of at least a part of theretaining member.

The retaining member may extend at least part way through the openingwhich can conveniently be located in an end face of the cap. Forexample, the retaining member may in one arrangement comprise a threadedbolt which is received within an internal threaded bore in the stud. Anend portion of the bolt may be extended axially away from the bore topass through the opening in the end face of the cap.

The portion of the retaining member that passes through the opening maybe of a different colour to the external surface of the cap thatsurrounds the opening to make it easier to identify. The protrudingportion may be fluorescent to aid identification in low-lightconditions.

The locking member may be a snap-fit onto the wheel nut, the wheel studor the retaining member. For example, the locking member may comprise acap with an inwardly directed protrusion that co-operates with a grooveor lip on one of the other components. Of course, other forms of“snap-fit” engagement are envisaged within the scope of the invention.

In an alternative, the cap may also include a magnet in addition to thesnap-fit engagement.

The retaining member may be so constructed and arranged to permitlocation of a socket onto the wheel nut without removing the retainingmember.

An advantage of such an arrangement is that it allows the wheel nut tobe tightened down using a socket without removing the retaining member.

Where the wheel nut has a standard hexagonal profile and retainingmember comprises a bolt, it is preferred that the maximum radial extentof the retaining member away from its central axis is smaller than theminimum radial extent of the flats of the wheel nut. In this case, thewheel nut can be engaged by an appropriate socket body for any positionof the retaining member. Of course, this assumes that the retainingmember is axially aligned with the wheel nut.

The retaining member may comprise a bolt which is received in aninternal bore provided in the wheel stud. Alternatively, it may comprisea retaining nut which is received upon a threaded extension of the wheelstud. In each case, the minimum radial extent of the head of theretaining member must be larger than the inner thread diameter of thewheel nut.

The retaining member may, in an alternative, comprise at least twodiscrete components. It may comprise a washer and a retaining bolt ornut, the washer being held between one face of the wheel nut and thehead of the retaining bolt or retaining nut. In this case, a smaller nutor bolt may be used as long as the diameter of the washer exceeds theinternal threaded diameter of the wheel nut. The locking member may beadapted to co-operate with both the wheel nut and the bolt or nut of theretaining member.

The washer may have a circular outline or may have another irregularshape. It may be made of a different material to the retaining nut orbolt. The washer may be aluminum for lightness with the nut or boltbeing of ferrous material. The cap may be provided with a magnet, orseveral magnets, that engage the nut or bolt.

An advantage of such a two-part construction for the retaining member isthat weight can be saved. A retaining member made from one piece offerrous material would be heavier for a similar size.

BRIEF DESCRIPTION OF THE DRAWINGS

There will now be described, by way of example only, several embodimentsof the present invention with reference to the accompanying drawings ofwhich:

FIG. 1(a) is an exploded cross-sectional view and 1(b) is acorresponding assembled view of a first embodiment of a wheel nutassembly in accordance with the present invention;

FIG. 2(a) is an exploded cross-sectional view and 2(b) is acorresponding assembled view of a second embodiment of a wheel nutassembly in accordance with the present invention;

FIG. 3(a) is an exploded cross-sectional view and 3(b) is acorresponding assembled view of a third embodiment of a wheel nutassembly in accordance with the present invention; and

FIG. 4 is a view of the locking cap used in FIGS. 1 to 3 of theaccompanying drawings (a) from above, (b) from the side; and (c) fromunderneath the cap.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A first embodiment of the present invention is shown in an exploded formin FIG. 1(a) of the accompanying drawings and in its assembled form inFIG. 1(b).

The wheel nut assembly comprises a stud 1 which is attached at one end 1a onto a hub (not shown). The stud 1 can be welded in place. The stud 1has an external thread 2 provided over at least its uppermost portionspaced from the hub. A wheel nut 3 is adapted to threadedly engage withthe stud 1 by means of an internal thread (not shown) which co-operateswith the external thread 2 on the stud 1. The nut 3 may be tightened tothe required torque using a socket or wrench and acts to trap a part ofthe vehicle wheel (not shown) onto the wheel hub.

The thread 2 on the stud 1 is of greater length than the thickness ofthe nut 3 so that when the wheel nut is fully tightened onto the stud,an end portion of the stud 1 protrudes from the wheel nut 3.

An internal bore 4 is provided in the protruding end portion of the studdistal from the wheel hub 2. The internal surface of the bore 4 isprovided with a thread 5 which is of the opposite hand to the externalthread 2.

A retaining member is provided in the form of a bolt having a head 6 anda threaded shank 7 that is complementary to the internal thread 5 in thebore 4. The bolt can be tightened into the bore 5 by engagement ofthread 7 with thread 5 and turning the bolt in the opposite direction tothat required to tighten the wheel nut 2.

A locking means in the form of a cap 8 is also provided. The locking cap8 is adapted to fit over and co-operate with both the wheel nut 3 andretaining bolt 6. The inside of the cap 8 has a multi-faced profile, asshown in FIG. 4 of the accompanying drawings. When fitted, the inside ofthe cap co-operates with the wheel nut 2.

The head 6 of the retaining bolt 6 has a stepped outline and in useextends through an opening 9 provided in the end of the cap 8. Thisallows the location of the retaining member to be visually identified.The opening in the cap has a profile that complements that of the bolt 6so that when fitted the cap prevents rotation of the bolt 6. A smallgroove around the head 6 also protrudes through the cap 8 and canreceive a circlip (not shown) that prevents accidental release of thecap 8 from the bolt 6.

The outer face of the cap is provided with indicia, in the example inthe form of an arrow. This enables the orientation of the cap to bevisually identified from a distance. Also, the portion of the retainingmember that protrudes through the opening of the cap has a differentcolor to that of the cap surrounding the opening so that it can beeasily identified.

Several modifications are envisaged within the scope of the invention astypified by the alternative embodiments of FIGS. 2 and 3 of theaccompanying drawings. Where possible the reference numerals used inFIG. 1 have been used in FIGS. 2 and 3 to denote like components.

In the alternative embodiment shown in FIGS. 2(a) and 2(b) of theaccompanying drawings, the portion of the retaining member that extendsthrough the cap has fewer facets, as does the complementary opening inthe cap 8. This restricts the number of possible combinations of cap andretaining member angular position.

In a still further modification shown in FIG. 3(a) and FIG. 3(b) of theaccompanying drawings the one-piece retaining member of the first andsecond embodiments is substituted by a two-part retaining member. Theretaining member comprises a bolt 20 and a washer 21 which is locatedbetween the head of the bolt 20 and the wheel nut 2. The washer 21 ismanufactured from a light weight material, such as aluminum, whilst thebolt is manufactured from a ferrous material. A circular magnet 22 isprovided on the cap to retain the cap 8 to the bolt 20.

1. A wheel nut assembly for fixing a wheel to a vehicle hub, the wheelnut assembly having a wheel nut, the wheel nut having an internalthread, the wheel nut assembly further comprising: a wheel stud havingan external thread adapted to co-operate with the internal thread of thewheel nut, and further having an internal thread; a retaining memberhaving an external thread of an opposite hand with respect to theinternal thread of the wheel stud for cooperating with the internalthread of the wheel stud; and a locking member adapted to engage boththe retaining member and a perimeter of the wheel nut to preventrelative movement there between and further adapted to permit a locationof the retaining member to be visually identified when the lockingmember is engaged to both the retaining member and the perimeter of thewheel nut.
 2. The wheel nut assembly of claim 1, wherein the lockingmember comprises a cap that at least partially covers the wheel nut andthe retaining member.
 3. The wheel nut assembly of claim 2, wherein thecap is provided with an opening which permits viewing of at least a partof the retaining member.
 4. The wheel nut assembly of claim 3, whereinthe cap comprises an end face, the opening is located at the end face,and at least a portion of the retaining member extends at leastpartially through the opening.
 5. The wheel nut assembly of claim 4,wherein the cap comprises an external surface that surrounds theopening, and the portion of the retaining member that extends at leastpartially through the opening is of a different color to the externalsurface of the cap that surrounds the opening.
 6. The wheel nut assemblyof claim 4, wherein the portion of the retaining member that extends atleast partially through the opening is fluorescent.
 7. The wheel nutassembly of claim 4, wherein the retaining member further includesanother portion that does not extend through the opening, the portion ofthe retaining member that does extend at least partially through theopening has fewer facets than the other portion that does not extendthrough the opening, and the locking member has a complementaryarrangement of facets with respect to the fewer facets of the portion ofthe retaining member that does extend at least partially through theopening to restrict a number of possible combinations of locking memberand retaining member angular position.
 8. The wheel nut assembly ofclaim 1, wherein the locking member is adapted to snap-fit onto at leastone of the wheel nut, the wheel stud and the retaining member.
 9. Thewheel nut assembly of claim 1, wherein the retaining member further hasa head portion, the head portion having a groove adapted to receive aclip to prevent accidental release of the locking member from theretaining member.
 10. The wheel nut assembly of claim 1, wherein thelocking member has an outer face having indicia disposed thereon topermit the location of the retaining member to be visually identifiedwhen the locking member is engaged to both the retaining member and thewheel nut.
 11. The wheel nut assembly of claim 1, wherein the retainingmember comprises a bolt and a washer, the bolt has a head, the washer isadapted to be disposed between the head of the bolt and the wheel nut.12. The wheel nut assembly of claim 11, wherein the bolt comprises aferrous material and the locking member further comprises a magnet toretain the locking member to the bolt.
 13. The wheel nut assembly ofclaim 12, wherein the magnet has a circular shape.
 14. A wheel nutassembly for fixing a wheel to a vehicle hub, the wheel nut assemblyfurther comprising: a wheel stud having an external thread adapted toco-operate with an internal thread of a wheel nut and further having abore and an internal thread disposed within the bore; a retaining memberhaving an external thread of an opposite hand with respect to that ofthe internal thread of the wheel stud for cooperating with the internalthread of the wheel stud; and a locking member adapted to engage boththe retaining member and a perimeter of the wheel nut to preventrelative movement there between and further adapted to permit a locationof the retaining member to be visually identified when the lockingmember is engaged to both the retaining member and the perimeter of thewheel nut.
 15. The wheel nut assembly of claim 14, wherein the lockingmember comprises a cap that at least partially covers the wheel nut andthe retaining member.
 16. The wheel nut assembly of claim 15, whereinthe cap is provided with an opening which permits viewing of at least apart of the retaining member.
 17. The wheel nut assembly of claim 16,wherein the cap comprises an end face, the opening is located at the endface, and at least a portion of the retaining member extends at leastpartially through the opening.
 18. The wheel nut assembly of claim 17,wherein the cap comprises an external surface that surrounds theopening, and the portion of the retaining member that extends at leastpartially through the opening is of a different color to the externalsurface of the cap that surrounds the opening.
 19. The wheel nutassembly of claim 14, wherein the retaining member further has a headportion, the head portion having a groove adapted to receive a clip toprevent accidental release of the locking member from the retainingmember.
 20. The wheel nut assembly of claim 14, wherein the retainingmember comprises a bolt and a washer, the bolt has a head, the washer isadapted to be disposed between the head of the bolt and the wheel nut.21. The wheel nut assembly of claim 14, wherein the locking member isadapted to snap-fit onto at least one of the wheel nut, the wheel studand the retaining member.
 22. A wheel nut assembly for fixing a wheel toa vehicle hub, the wheel nut assembly having a wheel nut, the wheel nuthaving an internal thread, the wheel nut assembly further comprising: awheel stud having an external thread adapted to co-operate with theinternal thread of the wheel nut, and further having an internal thread;a retaining member having an external thread of an opposite hand withrespect to the internal thread of the wheel stud for cooperating withthe internal thread of the wheel stud; and a locking member adapted toengage both the retaining member and the wheel nut to prevent relativemovement there between and further adapted to permit a location of theretaining member to be visually identified when the locking member isengaged to both the retaining member and the wheel nut, wherein thelocking member is adapted to snap-fit onto at least one of the wheelnut, the wheel stud and the retaining member.